Preparation And Modification Of Cyclic Peptide/GPTMS Hybrid Material For Vascular Stents

Vascular tissue engineering is a new method to solve the problem of insufficient migration sources for cardiovascular diseases.Currently,there are some problems in small-diameter vessels such as thromboembolism in clinic application.Hence,the crucial to solving the above problem is to search for suitable materials and methods which fabricate tissue engineering scaffolds.The ideal scaffold material should possess non-toxic,harmless to people,good mechanical property,blood compatibility and biological activity.In other words,it supports cell adhesion and growth,and ultimately endothelialization.Peptides are widely used in scaffold research due to their good biocompatibility and biological activity.However,it is hard to meet demand,due to the possibility of obtaining viruses from foreign bodies during the purification of natural polypeptides,and mechanical properties of natural polypeptides are generally poor.In this paper,the L-tyrosine was selected as a raw materials and cyclic dipeptide(CYC)was synthesized to avoid the problems of natural peptides,which increase the strength of the material.The CYC/GPTMS hybrid materials were prepared by sol-gel method that uses ?-glycidoxypropyltrimethoxysilane(GPTMS)and CYC as main raw materials.After optimizing the reaction temperature,the structure,mechanical property,hydrophilicity,cytocompatibility and other properties of the material were studied when the CYC content is 0,0.9%,1.8% and 2.7%.The results showed that no new chemical bond was formed between the CYC and GPTMS components.Compared with the GPTMS material obtained by hydrolysis,the Young's modulus and compressive strength of CYC/GPTMS hybrid materials are significantly increased.The Young's modulus and compressive strength can both reach 9.14 ± 1.56 MPa and 23.72± 3.13 MPa,respectively.The brittleness of the material increased,and the maximum was(24.4 ± 3.25)%.The surface hydrophilicity of the material was worse,and the water contact angle of CYC/GPTMS material was the largest(84.2 ± 4.3°),when CYC content was 2.7%.Due to the adhesion and proliferation of cells on CYC/GPTMS materials were enhanced.However,due to the poor hydrophilicity of the material,the adhesion and proliferation ability of the cells still had a certain gap compared with the coverslip.In order to improve the surface hydrophilicity and toughness of the material,polyethylene glycol(PEG)was used for surface modification.CYC/GPTMS/PEG composite materials with different PEG content were prepared via sol-gel method.According to the research on the structure,mechanical properties,hydrophilicity and cytocompatibility of materials,the main conclusions shows as follows: The different components of CYC/GPTMS/PEG materials are combined by intermolecular forces,hydrogen bonds and other secondary bond forces.Compared with CYC/GPTMS material,the compressive strength of CYC/GPTMS/PEG material was slightly reduced,the toughness was significantly enhanced,and the maximum strain was(58.7 ±6.46)%.With the PEG content increasing from 1.5% to 6%,the hydrophilicity of the material gradually increased.The adhesion and proliferation ability of cells were enhanced,and the absorbance value of cells cultured on CYC/GPTMS/PEG for 3 days was close to coverslip when PEG content was 4.5% and 6%.In addition,the swelling rate and blood compatibility of CYC/GPTMS/PEG materials were further studied.The results showed that the crosslinking degree and swelling rate of CYC/GPTMS/PEG composites increased and decreased respectively when the PEG content increased from 1.5% to 6%.With the increase of PEG content,the number of adherent platelets and denatured platelets on the material are both decreased,and the anti-thrombogenetic effect was enhanced.As the PEG content increases,the hemolysis rate decreases.The hemolysis rate of CYC/GPTMS/PEG materials with different PEG content is less than 5%,which meets the standards of biomedical materials.